Turbine engine components, such as turbine blades and vanes, are operated in high temperature environments. To avoid structural defects in the components resulting from their exposure to high temperatures, it is necessary to provide cooling circuits within the components. Turbine blades and vanes are subjected to high thermal loads on both the suction and pressure sides of their airfoil portions and at both the leading and trailing edges. The regions of the airfoils having the highest thermal load can differ depending on engine design.
In addition to thermal load problems, cooling film exit holes on such components can frequently become plugged by contaminants. Such plugging can cause a severe reduction in cooling effectiveness as the flow of cooling fluid over the exterior surface of the component is reduced.
Refractory metal core technology offers the potential to provide better cooling for turbine airfoils. Refractory metal core technology allows thin cooling circuits to be placed just under the surface of the airfoil and allows cooling fluid to be expelled into the gaspath. However, state of the art cooling circuits made using refractory metal cores have offered limited configurations in which the cooling fluid is expelled into the gaspath at favorable surface angles to allow effective film cooling.